Sheffield United have reluctantly allowed Chris Morgan to leave Bramall Lane to further his career.
The Blades stalwart will leave his role as Under 21s Coach to become First Team Coach to Danny Wilson at Chesterfield.
Morgan, who first joined United in the summer of 2003, leaves with United's thanks for his service, loyalty and commitment, as well as best wishes.
Nigel Adkins commented: "We wish Chris well, he is a legend at this Football Club and he will always be welcome back. This is a great opportunity for him to work closely with an experienced manager as he looks to develop his own career."
Morgan, 38, played 279 times for the Blades, scoring 15 goals. He was captain of the Club when promotion to the Premiership was secured and also played 24 times in the top flight.
Signed by Neil Warnock from Barnsley, he worked under a number of managers but a serious knee injury in 2010 forced his early retirement from the game.
Under Wilson he made a smooth transition to the Club's coaching structure and for the past couple of years has been responsible for the development of a number of young players as the lead Under 21s coach, as well as various first team duties. Twice he has acted as Caretaker Manager.
In the summer of 2015, over 12,000 supporters turned out to see the Blades match Newcastle United in his testimonial fixture, in which he played the last couple of minutes.
United's Technical Board is underway with discussions for a replacement.